The Electron Microscopy Core Facility provides readily accessible services to members of the University of Chicago Cancer Research Center for electron microscopic and cytochemical data collection. The facility provides immunocytochemistry and videoenhanced light microscope (VELM) services as well as electron microscopy. The EM Facility is equipped with both transmission and scanning electron microscopes with ancillary equipment suitable for all levels of microscopy. Full time technical assistance is available for consultation regarding projects, to prepare specimens from the time of fixation, to embedding, sectioning, microscopy and interpretation of photographs. The Facility provides special opportunities for immunolocalization of molecules either in frozen thin sections or Lowicryl-embedded samples. In collaboration with Dr. Robert Josephs, detailed analyses of individual molecules are available with a newly purchased Philips CM-120 electron microscope equipped with a cold transfer stage for viewing specimens at -170 degrees C. The VELM facility assists Cancer Center members to carry out qualitative and semi- quantitative analysis of the distribution of biological molecules within cells in normal, pathological and experimental conditions, using high resolution light microscopic cytochemistry.